Thermally controlled machine tool



Nov. 4, 1947.

Fig.1

M. KRONENBE RG ET AL THERMALLY CONTROLLED MACHINE TOOL Filed March 6, 1944 2 Sheets-Sheet 1 1N VENTOR5 /74x Mao mama [fmxs fP/vqr ATTO EY.

M. KRONENBERG EFAL 2,430,127

THERMALLY CONTROLLED MACHINE TOOL Filed March 6, 1944 2 Sheets-Sheet 2 Patented Nov. 4, 1947 2,430,127 THERMALLY CONTROLLED MAcnmirrgoL Max Kronenberg and Hans Ernst, Cincinnati, Ohio, assignors to The Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of Ohio Application March 6, 1944, Serial No. 525,284

11 Claims. 1

This invention relates to milling machines and particularly to a system for controllin the temperature of those parts of a milling machine which are subject to localized heating during the operation of the machine.

An object of this invention is to provide in a milling machine efllcient and effective means for controlling the temperature of certain parts of the machine and of the lubricant therefor that are subject to temperature changes during operation.

Another object is to provide means in a milling machine for maintaining the correct relationship between various parts of the machine that are subject to temperature changes during operation so as to retain the efllciency and accuracy of the machine under all operating conditions.

Another object of this invention is to provide in a milling machine, having certain parts that are subject to temperature changes during operation, means for circulating lubricating fluid in thermal transmitting relationship to said parts to maintain said parts and lubricant substantially at a desired temperature.

And a still further object is to provide a temperature control and lubricant distributing system for a milling machine transmission organization which effectively provides lubrication for all of the operating parts of the machine while dissipating localized heating which may develop in some of the operating parts of the machine and distribute said heat throughout the entire machine structure so as to effect a minimum temperature change uniformly distributed throughout the machine structure.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings forming a part thereof and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Figure 3 is a fragmentary enlarged section on the line 3 -3 of Figure 2.

Figure 4 is a fragmentary enlarged sectional tion and the utilization of a large amount of power for driving the spindle at these high rates of cutting speed. Because of these increased speeds and increased power transmission through the machine tool or milling machine, difficulty has been experienced with localized heating of certain of the machine parts, in particular the bearings, the cutter spindle, and the driving gear transmission for rotating the spindle. In order to maintain a high degree of accuracy in the finished work piece it is customary to closely ad- Referring to the drawings in which similar just or preload the main cutter spindle bearings so as to prevent any lateral shifting of thecutter spindle with respect to the column of the machine. When the above-mentioned high speed rotation of the spindle is effected, however, the precise adjustment of the spindle bearings results in heat being developed in the bearing races which is transferred to the machine frame or column at localized points of mounting of these hearings causing irregular expansion of the machine column. As a result, the distance between tool and work changes, causing inaccurate finished surfaces to be machined on the work piece.-

Also, because of the high speed operation of the machine, heat is generated in the lubricant due to the rapid compression and agitation of the lubricating fluid by the rapidly moving parts of the machine,

For illustrative purposes this invention is shown applied to a milling machine structure having a main frame or column III in which is journaled the cutter spindle II on a front main bearing indicated generally at l2, an intermediate main bearing indicated at l3 and a rear bearing Id. The front main bearing I! in this specific embodiment is of the tapered roller bearing type having an inner race l5 fixed to the bearing portion 18 of the cutter spindle ll upon which operate the rollers ll which in turn engage the outer race l8 of the hearing. The outer race is carried in a bore Illa formed in the column l0 so as to take care of radial loads on the spindle and thrust loads toward the left as indicated in Figures 1 and 3. Intermediate bearing |3 comprises an inner race |9 which nicely fits in sliding engagement on the bearing portion 20 of the spindle II and upon which operate the rollers 2| which in turn engage the outer race 22 fixed in the bore lfld of the intermediate wall llle of the machine frame or column Ill. The bearing I3 is capable of taking care of radial loads on the spindle H and thrust loads in an axial direction toward the right as seen in Figures 1 and 3.

In order to maintain the bearings I2 and I3 in proper running relationship an adjusting nut 24 mounted on the threaded portion 25 of the cutter spindle H is provided which abuts against the inner race IQ of the bearing |3 so as to urge it to the right, Figure 3, and cause the inner race l5 of the bearing |2 to engage the flange portion 25 of the cutter spindle I! so that by-drawing up on the nut 24 these inner races l9 and I5 may be moved toward each other to adjust the respective rollers l1 and 2| into-proper running contact with the outer races I5 and 22 in the column [0 of the machine to in this way provide an accurate rigid running condition for the spindle The rear bearing M for the spindle |l serves only to take care of radial movements of the work spindle at that point and essentially provides a steadying journal for the rear portion of the spindle.

The cutter spindle ll may be driven by any suitable prime mover such as an electric motor (not shown) which drives the main driving clutch pulley 21, Figure 1. This clutch pulley is connected or disconnected in driving relationship with the pulley shaft 28 by any conventional clutch mechanism incorporated therein. This shaft 28 is mounted on suitable bearings 29 and 39 in the frame or column I!) of the machine and is also supported by bearings 3| and 32 of the clutch mechanism in the pulley 21 which, in turn, is supported on bearings 33 directly in the column ID of the machine. On the pulley shaft 28 are the sliding driving gears 34, 35 and 35 which are respectively slidable'into driving engagement with the gears 31, 3B and 39 fixed to a shaft 40 carried in suitable bearings 4| and 42 in the column ID of the machine. Associated with the shaft 40 is shaft 43 journaled in bearings 44 and 45 in the column III on which is slidably mounted in driving relationship a gear couplet comprising the gears 45 and 41 which may be respectively engaged with the gears 39 and 48 fixed on the shaft 40.

On the shaft 43 is slidably mounted in driving relationship a reversing gear to efiect rotation of the spindle II in one direction or the other comprising a shiftable gear 49 which may be slid axially gear 59 of e gear couplet 505| on a shaft 5|a journaledi'n bearings 5|b and 5Ic in column In, or to directly engage a gear 52 fixed on a shaft 53 journaled in suitable bearings 54 and 55 in the column l0. When the gear 49 is in engagement with the gear 50 the drive from the shaft 43 passes through gear 49, the gear couplet 5ll5| to the gear 52 on the shaft 53 and when the gear is shifted to the left, Figure 1, on the shaft 43 the drive therefrom is transmitted directly from the gear 49 to the gear 52 to effect reverse in the shaft 53.

v Three changes of speed drive to a back gear shaft 55 from the shaft 53 are effected by means comprising a low speed drive from a gear 51 the shaft 43 to either engage a fixed on the shaft 53, which is adapted to be engaged by the gear 58 of the gear couplet 58-59 when this couplet is shifted to the right, Figure 1; an intermediate speed driving of the back gear shaft 55 obtained by shifting the gear couplet 58 59 to the left, to engage its gear 59 with a gear 50 fixed on the shaft 53, and a high speed driving of the back gear shaft 55 by engaging a clutch 5|, when the gear couplet 58-59 is in neutral as shown in Figure 1 which couples the gear 52 journaled on the shaft 53 in driving relationship with said shaft so that the gear 62 then drives the high speed gear 53 fixed on the back gear shaft 55.

The back gear shaft 55 is iournaled in suitable bearings 64, 55, and 56 in the column l0 and carries a low speed shiftable back gear pinion 51 axially slidable in driving relationship on the shaft 55 for engagement with the large face gear 58 fixed on the cutter spindle H. The pinion 61 also has clutch teeth 59 engageable with appropriate mating clutch teeth in the hub portion 19 of the high speed driving gear I! journaled on the back geanshaft and which is constantly in mesh with a gear 12 fixed on the cutter spindle I. In this way is provided a change speed transmission in the column of a milling machine for driving the cutter spindle through a wide range of different, speeds and particularly providing a high speed drive for the spindle through the gears 52-53 and Ii-12 when utilizing carbide cutting tools at high cutting speeds.

The cutter spindle H and the machine frame or column H! are affected by heat arising from the interaction of the cutting tool with the work and heat generated by the rolling action particularly in the main bearing l2 of the work spindle |l. When an arbor and especially when a face milling cutter is mounted directly on the spindle nose Ila heat generated in the body of the cutter during the cutting operation is transferred to the work spindle l| causing it to expand and change the adjustment of the spindle bearings l2 and I3. This results in looseness and in inaccurate rotation of the work spindle about its true axis. Also the front main bearing l2 for the cutter spindle l which sustains the major part of the forces imparted to the work spindle by the interaction of the cutter and work piece, generates heat as the rollers l1 roll around the races l5 and I8 due to inherent rolling friction in such bearings and also heat developed by the mechanical working of the lubricant by the rollers operating against the races in the bearing.

As a result, heat is transferred by the inner race l5 of the bearing |2 to the spindle Heat is also conveyed through the outer race If! to the bore Illa of the column |0 causing the associated portion of the column in the vicinity of the bearing 2 to be locally heated. As a result, the front wall lb of the column tends to absorb heat and expand while the rear wall lflc of the column remains relatively cooler and unchanged causing the front bearing l2 and the spindle H to be raised upwardly relative to the rear bearing, thus causing misalignment of the work spindle from its true horizontal position and consequent inaccuracy in the work being machined. There are also various temperature changes which take place in the shafts of the change speed transmission for the cutter spindle due to the operation of the bearings supporting these shafts and the interaction of the gears mounted on these shafts which results in misalignments in the transmission, creating noise and vibration in the" the work. 1 Y

In order to minimize theabove-stated localized Y heating and distortlonand'reduce the overall heat developed in the machine structure, apparatus is provided for conducting thelocalizedheating away. from the heatv generating :areas' and dis.-.

84, continuously driven by any suitable means such as the gear 84a connected to the clutch pulley 21 which is continuously rotated by a suitable prime mover (not shown), which withdraws 1u bric'ant through a line 85 from the reservoir 8|" I and transmits-fluid under pressure through a, line 86 to a port 81 of an automatic control valve 88 tributing the heat uniformly throughout'the machine structure.

Heat generated in the tool spine die is absorbed by a heat radiator mounted thereon as best seen in Figure 3. The largeface gear 68 has a tapered bore 13 which securely fits over the tapered portion." formed'onthe cutter; spindle II. This gear 68 is held against the tapered portion 14 by a clamping-nut licarried onthe threaded portion 16,0f the spindle II, the nut engaging the gear 12 and a spindle heat, radiating device or radiatorin the form of a finned collar- 11 having annular fins 11a formed on its periphery. Both the gear 12-and the spindle heat radiator 11' closely fit the portion 18a of the spindle I I and abut against the gear 88 so that when the unt 15 is securely tightened the gear 12, the

, 12 mounted thereon, maybe absorbed and removed from the spindleiby the radiating fins 11a of the spindle heat'radiator 11, especially when a lubricant and cooling medium-is caused to continuously precipitate upon and flow through the spaces between the-fins 11a during the operation ofthemachine.

Heat is absorbed from the front main bearing I2 for the cutter spindle I I by the annular-shaped front bearing heat radiating device or heat radiator 18 which nicely fits in heat exchanging relationship in a bore 19 formed in the column I8 and firmly abuts against the inner face 88 of the bore 19 and closely adjacent the outer race I8 of the bearing I2 so as-to directly receive and absorb any heat generated in the outer race I8 which may be transmitted through the bore I8a to theport'ion of column adjacent the annular radiator 18, and thereby tends to intercept or absorb heat transferred to the" column I8 by the outer bearing race I8 of the bearing I2.

A combined lubricating and temperature control system cooperating with said spindle heat radiator and front bearing radiator is provided for the milling machine transmission organization comprising a main supply reservoir 8| formed in the column I8 below the transmission mechanism of the machine as best illustrated in Figure 1. Preferably, this reservoir is of large capacity for effectively maintaining the lubricating fluid at a uniform minimum temperature and to distribute any temperature rise in the fluid evenly throughout the lower portion of the machine column I8. Fluid from the reservoir is utilized to actuate certain power operated devices of the machine such as a servo-clutch control mechanism indicated generally at 82, and a hydraulic gear shifting control valve mechanism, indicated generally at 83. The system isalso utilized to effect the proper lubrication of all of the moving parts of the above transmission and to dissipate and 4 machine.

and-also transmits pressure through the line 86,

. abranch'line 88a through a check valve 89 and line 89a to the high pressure line 98 which is connected through lines 9| and 92 to the servoclutch control mechanism 82 for the clutch pulley 21 and through. a line 93 for the fluid pressure control Ivalve 83 for effecting power shifting of thevarious shiftable gears 3435, 36, 48-41, 58-59 and 81, and the clutch SI for effecting speed changes in the spindle I I. Since the servoclutch control mechanism 82 and the fluid pressure gear shifting control valve 83 and associated mechanism are, of well-known construction and form no specific part of this invention, further detailed description of this apparatus will not be undertaken. A high pressure pump, indicated gener-' ally at 94, may also be driven from the gear 84a of the pulley 21. This pump withdraws fluid through a line 95 from the reservoir BI and transmits pressure through the line 96 to the line 98, 9|, and 92 to the servo-clutch control valve 82 and through the line 93 to the power gear shift control valve 83. A branch line 91 interconnects a closed pressure chamber 98 in the valve 8-8 so as to force the plunger 99 to the left, Figure 1, against a spring I88 until it abuts against the screw 88 when high pressure? builds .up in the line 98--9I after the connected servo-clutch control valve 82 and fluid-pressure gear shifter control valve 83 have moved to idesired predetermined positions. When this pressure builds -up in chamber 98 to move the valve plunger 99,"groove I83 in the valve plunger 99 is moved into communication with the port 81 and with an exhaust port I84*- connected to the line I82 which supplies the m1 gear pump flow to the lubricating and cooling system of the At the same time the port 98a of the valve 88 is opened a predetermined restricted amount to drain line 98b which returns the fluid to reservoir M by appropriate setting of the screw 88a to maintainv the desired high Pressure in chamber 98 and line 92. The pump 84 functions to assist the pump 94 when actuating the servoclutch control valve 82 and the gear shifter control valve 83 in making changes therein by providing an additional supply of fluid through the check valve 89 and line 89a.

Thus, during the normal operation of the machine -in performing cutting operations on the work, fluid pressure delivered by the pump 94 through the lines 98 and 98, the branch line 91, to the pressure chamber 98 of the valve 88, holds the valve plunger 99 in a shifted position to connect the pump 84 to the line I82 which has a branch line I88 connected into the annular cavity I81 of'the front bearing heat radiator 1-8 for the bearing I2. Discharge from the annular cavity I81 passes out through a line I88 which conducts the fluid which has absorbed the heat from the front bearing I2 to an outlet point I89 from which it precipitates down against the rear wall We of the machine column I8 and-returns to the reservoir 8i. By this arrangement heat is absorbed from the bearing I2 as the fluid passes remove localized heating conditions which may from the line I88 through the cavity I81 of the radiator 18 and this heat is carried away by the fluid passing out through the line I88 and conducted against the rear wall Me of the column 7 It so as to convey a certain amount of heat to cause this rear wall to cause its expansion to take place commensurate with the expansion of the front wall "lb of the column so that there will be a uniform distribution of heat in these two wall portions of the machine frame. It is obvious that this is desirable since it is not possible to completely remove all heat received from the bearing I2 by means of the radiator I! so that a certain amount of compensating heat distribution to the rear wall We from the front wall III?) is effective to maintain proper alignment of the work spindle II in the column IIl.

Also, a certain amount of lubricant from the cavity IIlI in the front bearing radiator I8 is permitted to escape through a fluid resistance comprising a stud H2, as best seen in Figure 4, fixed in the bore 18a of the radiator I! through which is provided an axial bore H3 terminating in a diametral bore H4 which opens into an annular groove H5 surrounded by a sleeve H5 mounted on the threaded portion H1 of the stud I I3 so that fluid escapes from the annulargroove H5 through the threaded portion between the sleeve H6 and the threaded portion III of the stud H2 at a predetermined desired rate. The lubricant escapes through the opening H8 in the end of the sleeve H8 and passes into the chamber H9 formed by the front bearing cover plate IISa where it may flow over the bearing rollers I1 and races I5 and III of the front bearing I2. Excess fluid from the chamber I I9 passes out through a drain opening I20, Figure 3, formed in the front wall lb of the column I0 and out through an aligned drain opening I2I in the radiator I8 from which the fluid drains down the front wall 40b to return to reservoir 8|. -This drainage serves to provide a similar transfer of heat from the lubricant escaping from the chamber I01 and to dissipate this heat by washing through the front wall I Ilb of the column in the same fashion that the coolant is distributed at the point I09 to further equalize any heat expansion in the column III.

Referring to Figure 1, the line I02 also has a second branch line I22 to which is connected a lubricant distributing spray I23 located at the top of the column and transmission mechanism and particularly associated-with the spindle heat radiator 11 on the cutter spindle II. The fins 11a of the heat radiator 'I'I receive discharge from the lubricant spray I2! which continuously plays fluid over the spindle and radiator during operation of the machine. Heat developed in the spindle II thus is dissipated by means of the radiator 11 to prevent heat from accumulating which would otherwise cause expansion of the spindle with the resultant looseness and change in adjustment of the bearings I2 and I3, spray I23 also provides effective lubrication for the gears 61 and 68 and the gears II and I2 and associated bearings I3 and 65.

The line I22has a branch line I24 which continuously discharges fluid into an upper lubricant reservoir I25 formed in the column III of the machine. From this reservoir extends a series of lubricating discharge lines I26 which serve to deliver lubricant to the bearing I l on the rear of the spindle H. Lines I21 and I28 respectively provide lubrication for the bearing 66 of the shaft 56 and the bearing 55 of the shaft 53. A line I29 encore? III to bearings SI and 32 also associated with the driving pulley 21. A series of spray nozzles I32 are provided in the line I24 at the top of the column to provide lubricant which pours over the shafts 58, 53, Ma, 40, and 28 and associated bearmas and gearing otherwise not specifically lubricated from the spray I23 and reservoir I25 to thereby prevent localized heating and excessive temperature changesin these parts.

In this way a temperature control and lubricating system has been providedfor a milling machine to eifectively absorb localized heating which particularly develops in the column, cutter spindle, and driving transmission during the operation of the machine at high speeds and to dissipate this heat throughout the machine structure to increase the overall operating efficiency and accuracy of the machine.

What is claimed is: I

1. A temperature control system-for a milling machine having a column, a cutter spindle, and bearing means rotatably mounting said spindle in said column, including a bearing heat radiator -mounted on said column to receive heat generated by said bearing means, a spindle heat radiator comprising a series of axially spaced radially disposed fins fixed on said spindle in a position proximate the bearing to absorb heat imparted to said spindle by said bearing means, a, lubricant reservoir in said column, a pump for circulating fluid from said reservoir through said radiators to effect withdrawal of heat from said bearing and spindle during the operation of said machine,

2. In a milling machine having a column, a cutter spindle, and bearing means for rotatably supporting said spindle in front and rear walls of said column, the combination of a heat radiator associated with the bearing means in said front wall, a heat radiator associated with said spindle, a lubricant reservoir in said column, means for circulating lubricant from said reservoir through said heat radiators, and means for conducting the lubricant discharge from the radiator associated with the bearing means in the front wall to the rear wall of said column to equalize the temperature in both of said walls.

3. In a milling. machine having a column, front, rear, and intermediate walls in said column, a cutter spindle journaled in bearings against radial and axial movement in said front and intermediate walls and against radial movement in said rear wall, the combination of a front bearing temperature radiator mounted in the front wall of said column adjacent the bearing in said front wall, a fluid conducting cavity in said radiator, a lubricant fluid reservoir in said column, pumping means for supplyingfluid from said reservoir to sald'cavity to circulate said fluid therein in thermal transmitting relationship to said front wall and bearing, and means for conducting and distributing the discharge from said cavity in thermal transmitting relationship over the rear wall of said column.

4. In a milling machine having a column, a rotatable cutter spindle journaled in said column at a plurality of mounting positions, and bearing ,means for supporting said spindle at each of said positions, the combination of a heat radiator for one of said bearing means, a lubricant reservoir formed in said column, fiuid pressure delivertherein by the rotation of said spindle, and means for conveying fluid from said heat radiator at one mounting position to another mounting position so as to equalize the relative temperatures at said mounting positions.

5. In a milling machine having a column, a rotatable cutter spindle, a front bearing rotatably supporting said spindle in the front wall of said column, an intermediate bearing rotatably supporting said spindle in said column cooperating with said front bearing to accurately confine movements of said spindle both axially and radially under a preloaded operating condition, a rear steady bearing for said cutter spindle mounted in the rear wall of said column, the combination of a heat radiator mounted in said front wall of said column in thermal transferring relationship to said front bearing to receive heat generated therein during rotation of said spindle, a fluid reservoir in said column, a fluid pump receiving its supply of fluid from said reservoir,

distributing it in thermal transferring relationship on the rear wall of said column to effect equalization of the temperature in said walls.

6. In a temperature control system for a milling machine structure having a column, a cutter spindle, a front bearing rotatably supporting said spindle in the front wall of said column, an intermediate bearing supporting said spindle in an intermediate wall of said column and cooperating with said front bearing toconflne said spindle against axial and radial movements relative to said column, and a rear steady bearing for said spindle mounted in the rear wall of said column, the combination of a heat radiator mounted in said column adjacent said front bearing, a spindle heat radiator mounted on said spindle between said front bearing and said intermediate bearing, a lubricantfluid supply reservoir formed in the base of said column below said work spindle and supporting bearings, a fluid pressure pump adapted to withdraw fluid from said reservoir and deliver it to each of said radiwhereby the discharge from said radiator in the column for said front bearing discharges said fluid simultaneously in thermal transferring relationship on said front and rear walls of said column.

7. In a lubricating and temperature control system for a milling machine having a column, a

cutter spindle, front, rear, and intermediate walls formed integral with said column, bearings in each of said walls for rotatively supporting said cutter spindle, a change speed transmission in said column associated with said work spindle and adapted to operate said work spindle at a plurality of different cutting speeds, the combination of a lubricating fluid reservoir in the base of said column, a fluid pressure pump in said column driving its source of fluid from said reservoir, a heat radiator, receiving the discharge of fluid from said pump, associated with the bearing supporting said cutter spindle in said supplied with fluid from said pump, means for interconnecting said last-mentioned reservoir to a series of bearings supporting said change speed transmission in the rear wall of said column, and means whereby the discharge from said firstmentioned radiator is distributed in thermal transferring relationship on the rear wall of said column to effect equalization of the temperature in the front and rear walls of said column.

8. In a milling machine, a column having a front, rear, and intermediate wall formed integral therewith, a cutter spindle rotatively mounted in a bearing in each of said walls, a change speed transmission in said column adapted to rotate said cutter spindle at a plurality of different speeds, a lubricating fluid reservoir in the bottom of said column adapted to receive all lubricant delivered to said spindle, bearings, and change speed transmission, the combination of a heat radiator associated with the spindle bearing in said front wall mounted in said column to receive heat developed in said bearing and transmitted to said column, a heat radiator on said spindle adapted to receive heat developed in said spindle by said bearings or a cutter mounted on said spindle, a fluid delivery pump receiving fluid from said reservoir and transmitting it to each of said radiators, means for conducting exhausted fluid from said radiator associated with the front bearing in part to said front bearing and from said bearing to said front wall of said column and in part to the rear wall' of said column so as to equalize the temperatures in said front and rear walls of said column,- and means for conducting some of said fluid from said pump over the change speed transmission for said work spindle to lubricate and absorb heat developed therein.

9. In a milling machine, a column having a front, rear, and intermediate wall formed integral therewith, a cutter spindle rotatively mounted in a bearing in each of said walls, a change speed transmission in said column adapted'to rotate said cutter spindle at a plurality of different speeds, a lubricating fluid reservoir in the bottom of said column adapted to receive all lubricant delivered to said spindle, bearings, and change speed transmission, the combination of a heat radiator associated with the spindle bearing in said front wall to. receive heat developed in said bearing and column, a heat radiator on said spindle adapted to receive heat developed in said spindle by said bearings or a cutter mounted on said spindle, a fluid delivery pump receiving fluid from said reservoir and transmitting it to each of said radiators, means for conducting exhausted fluid from said radiator associated with the front bearing in part to said front bearing and front wall of said column and in part to the rear wall of said column so as to equalize the temperatures in said front and rear wall of said column, means ing machine. organization having 11 a hollow column, a cutterspindle and a drive transmission therefor contained within the column, a pair 0! bearing members carried by the column for rotatably supporting the spindle against axial movement, said cutter spindle and bearings being subject to heating due to the reaction of a cutter mounted on the spindle during a machining operation, the combination oi a lubricant supply system for the parts within the column including a fluid reservoir, an annular heat radiating device contained within the column in proximity to the spindle and in heat transferring relationship with the bearing, a second heat radiator directly mounted on thespindle intermediate the supporting bearings therefor, said second member having axially spaced peripheral cooling fins, a fluid supply pump, means for delivering fluid from the pump into heat transferring relation to both of said heat radiating devices whereby said fluid is brought into thermal transmitting relationship with said radiating devices to absorb the localized heat developed in the spindle and bearing during a machining operation, and means for distributing the fluid after engagement with the radiating devices throughout the hollow column to equalize the general temperature conditions in the machine structure.

11. The combination with a machine tool structure including a hollow frame unit, a rotatable spindle and a plurality of axially spaced bearing means for rotatably supporting said spindie in said frame, of means for thermally conditioning the structure to minimize unequal expansions therein comprising an internal liquid cooling annular ring circumscribing the spindle mounted on the frame in heat absorbing relation to one of the bearing means and a second annular member carried by the spindle intermediate said bearing means, said second member having a multiplicity of peripheral cooling fins, a lubricant reservoir, and means for circulating lubricant by way of said annular radiating means and in thermal transferring relationship thereto to remote portions oi the frame whereby equalization of temperature conditions therein is efiected.

MAX KRONENBERG. HANS ERNST.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS 

